CN114148044B - Graphene composite heat-conducting gasket and preparation method thereof - Google Patents

Graphene composite heat-conducting gasket and preparation method thereof Download PDF

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Publication number
CN114148044B
CN114148044B CN202111404548.9A CN202111404548A CN114148044B CN 114148044 B CN114148044 B CN 114148044B CN 202111404548 A CN202111404548 A CN 202111404548A CN 114148044 B CN114148044 B CN 114148044B
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adhesive
graphene
heat
graphene heat
conducting
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CN114148044A (en
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石燕军
葛翔
李峰
卢静
李壮
周步存
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Changzhou Fuxi Technology Co Ltd
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Changzhou Fuxi Technology Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/18—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by features of a layer of foamed material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/06—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the heating method
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/10—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the pressing technique, e.g. using action of vacuum or fluid pressure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/12—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by using adhesives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B38/00—Ancillary operations in connection with laminating processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B38/00—Ancillary operations in connection with laminating processes
    • B32B38/0004—Cutting, tearing or severing, e.g. bursting; Cutter details
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B38/00—Ancillary operations in connection with laminating processes
    • B32B38/04—Punching, slitting or perforating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B38/00—Ancillary operations in connection with laminating processes
    • B32B38/08—Impregnating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
    • B32B5/32—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed at least two layers being foamed and next to each other
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B38/00—Ancillary operations in connection with laminating processes
    • B32B2038/0052—Other operations not otherwise provided for
    • B32B2038/0064—Smoothing, polishing, making a glossy surface
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B38/00—Ancillary operations in connection with laminating processes
    • B32B38/04—Punching, slitting or perforating
    • B32B2038/047—Perforating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2266/00—Composition of foam
    • B32B2266/04—Inorganic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/30—Properties of the layers or laminate having particular thermal properties
    • B32B2307/302—Conductive
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/51—Elastic

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  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Sealing Material Composition (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
  • Carbon And Carbon Compounds (AREA)

Abstract

The invention provides a preparation method of a graphene composite heat-conducting gasket, which comprises the following steps: carrying out laser drilling on the graphene heat conduction foam film; impregnating the perforated graphene heat-conducting foam film through a first adhesive; stacking the impregnated graphene heat-conducting foam films layer by layer, placing the graphene heat-conducting foam films into a die, and applying pressure to attach adjacent graphene heat-conducting foam films; uniformly coating a second adhesive on the periphery of the pressed graphene heat-conducting foam film to enable the multi-layer graphene heat-conducting foam film to be completely coated into a block, wherein the curing temperature of the second adhesive is lower than that of the first adhesive; cutting the cured and formed block into sheets along the stacking direction; carrying out hot press molding on the sheet; carrying out surface polishing treatment on the sheet after hot press molding; and trimming the edge of the polished sheet, and removing the second adhesive coated on the edge to obtain the graphene composite heat-conducting gasket. The invention also provides a gasket. The invention has low thermal resistance and high rebound.

Description

Graphene composite heat-conducting gasket and preparation method thereof
Technical Field
The invention belongs to the technical field of heat conduction and heat dissipation, and particularly relates to a graphene composite heat conduction gasket and a preparation method thereof.
Background
A heat conduction gasket is a high-performance gap filling heat conduction material, and is mainly used for a transfer interface between electronic equipment and a radiating fin or a product shell. The graphene has good heat conduction performance and can be used as a reinforcing material of the heat conduction gasket. The modes of the heat conduction gasket prepared by adopting the graphene heat conduction film mainly comprise two modes: firstly, stacking and bonding graphene heat conducting films layer by layer through an adhesive, and then cutting the graphene heat conducting films into heat conducting gaskets to enable the graphene heat conducting films to be arranged along the thickness direction; secondly, the graphene heat conduction film is changed into a longitudinal arrangement from the plane direction in a folding mode, and then an adhesive is coated to form an integral structure.
The graphene heat conduction film adopted in the two modes has higher heat conduction coefficient, but the densified structure of the graphene heat conduction film leads to higher hardness of the prepared heat conduction gasket, and the application thermal resistance of the gasket is obviously increased; secondly, the graphene heat conduction film has a smooth surface, and surface roughening treatment, such as nano coating or polishing roughening, is often needed to realize good combination with the adhesive; in addition, the graphite-like structure inside the graphene heat conducting film is easy to cause layering, and the overall mechanical stability is affected.
Disclosure of Invention
Aiming at one or more of the problems in the prior art, the invention provides a preparation method of a graphene composite heat-conducting gasket, which comprises the following steps:
carrying out laser drilling on the graphene heat conduction foam film;
Impregnating the perforated graphene heat-conducting foam film through a first adhesive;
Stacking the impregnated graphene heat-conducting foam films layer by layer, placing the graphene heat-conducting foam films into a die, and applying pressure to attach adjacent graphene heat-conducting foam films;
Uniformly coating a second adhesive on the periphery of the pressed graphene heat-conducting foam film to enable the multi-layer graphene heat-conducting foam film to be completely coated into a block, wherein the curing temperature of the second adhesive is lower than that of the first adhesive;
Cutting the cured and formed block into sheets along the stacking direction;
Carrying out hot press molding on the sheet;
Carrying out surface polishing treatment on the sheet after hot press molding;
and trimming the edge of the polished sheet, and removing the second adhesive coated on the edge to obtain the graphene composite heat-conducting gasket.
Optionally, in the step of performing laser drilling on the graphene heat-conducting foam film, a plurality of through holes are formed in the graphene heat-conducting foam film, and the diameter of each through hole is 30-300 μm, and is lower than 30 μm, so that the vertical through effect is poor, and the first adhesive dipping effect is poor; if the particle size is more than 300 mu m, the mechanical property of the graphene heat-conducting foam film is reduced due to larger pores, and the graphene heat-conducting foam film is easy to crack, preferably 50-200 mu m.
Optionally, the average center spacing of the plurality of through holes is 100-600 μm, and the average center spacing is lower than 100 μm, so that the graphene heat-conducting foam film is too dense and is easy to crack; if the particle diameter is more than 600. Mu.m, the particle diameter is too large to affect the penetration effect, and is preferably 200 to 500. Mu.m.
Optionally, in the step of impregnating the perforated graphene heat-conducting foam film with the first adhesive, the first adhesive is one or more of epoxy resin, phenolic resin, furfural resin, polyurethane, acrylic resin or organic silica gel.
Optionally, the first adhesive is a silicone gel, preferably a liquid silicone gel.
Optionally, the liquid silicone is one or more of polydimethylsiloxane, alpha, omega-dihydroxypolydimethylsiloxane, polydiphenylsiloxane, alpha, omega-dihydroxypolymethyl3, 3-trifluoropropyl siloxane, cyanosiloxysilane, or alpha, omega-diethylpolydimethylsiloxane.
Optionally, the viscosity of the first adhesive is 50-800 mPas, the viscosity is lower than 50 mPas, and the mechanical property of the colloid is relatively poor, so that the mechanical property of the whole gasket is influenced; if the viscosity is higher than 800 mPas, the fluidity is poor, and the foam film is not easily impregnated, so that a large amount of air exists in the foam film, and the overall mechanical properties are affected, preferably 100 to 600 mPas.
Optionally, the first adhesive adopts the organic silica gel of heating curing mode, and open place (within 3 months) can not solidify under normal atmospheric temperature, only can slowly solidify under the heating environment, and the higher temperature solidification is faster, ensures that first adhesive is in the liquid state when sample cutting technology, and when hot pressing technology, first adhesive can play the effect of soaking again to utilize hot pressing temperature to solidify, thereby guarantee that the impregnating adhesive has better dipping effect.
Optionally, stacking the impregnated graphene heat-conducting foam films layer by layer in a mold, pressing to attach the films, cutting the graphene heat-conducting foam films into sheets with consistent sizes, stacking the sheets layer by layer in the mold, and then placing the sheets in the mold.
Optionally, in the step of uniformly coating the second adhesive on the periphery of the pressed graphene heat-conducting foam film, the second adhesive is mainly distributed on the surface of the foam film block body to play a role in shaping and fixing, so that the foam film block body is prevented from falling apart during cutting, hot pressing and polishing processes, the cutting formability is ensured, and the second adhesive is one or more of epoxy resin, phenolic resin, furfural resin, polyurethane, acrylic resin or organic silica gel, and is preferably epoxy resin.
Optionally, the epoxy resin is cured by heating, that is, when the graphene heat-conducting foam film is laminated and shaped and cured, the second adhesive can be cured by heating or cured at normal temperature, and considering the preparation efficiency, the heat-curable epoxy resin can be selected, preferably, the epoxy resin is cured by heating at 50 ℃, the curing temperature of the second adhesive is too high, so that the curing of the internal impregnating adhesive is easy to cause, and the re-impregnating effect of the second adhesive in the later hot-pressing process is affected.
Optionally, the viscosity of the second adhesive is 10000-200000 mPas, the viscosity is lower than 10000 mPas, the permeability is too good, and the second adhesive is easy to infiltrate into the interlayer of the foam film, thereby affecting the mechanical property of the gasket; if the viscosity is more than 200000 mPas, the foam discharging ability is poor and the handling property is poor, preferably 30000 to 150000 mPas.
Optionally, in the step of cutting the solidified and molded block into sheets along the stacking direction, the cutting mode adopts wire cutting, laser cutting, ultrasonic cutting, blade cutting or freezing cutting, and the thickness of the cut sheet is preferably 0.2-1mm.
Optionally, the step of hot press forming the sheet includes: and limiting the sheet by using a die and heating and curing the sheet.
Alternatively, the pressure is applied at 0.1-1.0MPa, preferably 0.3-0.8MPa.
Alternatively, the curing temperature is 100 to 160 ℃, preferably 120 to 150 ℃.
Optionally, the step of performing surface polishing treatment on the sheet after hot press molding includes: the polishing mode adopts contact polishing or non-contact polishing equipment.
Optionally, in the step of performing laser drilling on the graphene heat-conducting foam film, the heat conductivity coefficient of the graphene heat-conducting foam film is not less than 100W/(m·k), and if the heat conductivity coefficient is less than 100, the heat conductivity coefficient of the final gasket is too low, preferably not less than 150W/(m·k).
Optionally, the thickness of the graphene heat-conducting foam film is 100-300 μm, and the thickness is lower than 100 μm, so that the strength is lower, and the preparation is not facilitated; the thickness is higher than 300 mu m, the impregnated adhesive is not easy to enter the inside, the inside combination is poor, layering is easy to occur, and preferably, the thickness of the graphene heat-conducting foam film is 150-250 mu m.
Optionally, the density of the graphene heat-conducting foam film is 0.05-0.20g/cm 3, and the density is lower than 0.05g/cm 3, so that the graphene heat-conducting foam film is easy to crack; if the density is higher than 0.20g/cm 3, pores are smaller, the impregnated adhesive cannot enter the interior of the graphene foam, and preferably the thickness of the graphene heat-conducting foam film is 0.08-0.15g/cm 3.
Optionally, the graphene heat-conducting foam membrane is composed of graphene pore walls and pores, graphene is of a layered structure, certain pores exist between layers, a graphene disordered structure is an isotropic material, the final heat-conducting gasket is poor in directional heat-conducting effect, the average pore diameter of the pores in the graphene heat-conducting foam membrane is 10-50 microns, and preferably, the average pore diameter is 15-30 microns.
According to another aspect of the present invention, there is provided a graphene composite heat conductive gasket, including a plurality of graphene heat conductive foam films and an adhesive arranged along a thickness direction sheet, the graphene heat conductive foam films having a plurality of through holes thereon, the graphene heat conductive foam films having a ratio of 10wt.% to 50wt.%, and having a ratio of less than 10wt.% causing poor heat conductive effect due to too little graphene; above 50wt.%, the thermal pad tends to delaminate due to too little adhesive, and the mechanical properties are poor.
Optionally, the graphene heat-conducting foam film accounts for 15wt.% to 35wt.%, when the graphene heat-conducting foam film accounts for 15wt.% to 35wt.%, the content of the adhesive in the system is relatively high, and the adhesive plays roles of bonding and providing a network structure in the system, so that the mechanical properties of the gasket, including the strength and compression retraction elastic energy of the gasket, are improved.
According to the preparation method of the graphene composite heat-conducting gasket, the low-density graphene heat-conducting foam film and the adhesive are compounded to prepare the heat-conducting gasket, and the obtained graphene composite heat-conducting gasket has the characteristics of high strength, high rebound, high heat conduction in the thickness direction and low heat resistance.
According to the invention, after the graphene heat-conducting foam film subjected to laser drilling is immersed by a first adhesive, the graphene heat-conducting foam film is stacked layer by using a die and pressed and bonded, then a second adhesive is coated around the graphene heat-conducting foam film sample block to wrap the graphene heat-conducting foam film sample block for adhesion and fixation, after the second adhesive is completely solidified, the graphene heat-conducting foam film is cut into sheets along the lamination direction, finally the sheets are subjected to hot-pressing treatment and surface polishing to obtain the heat-conducting gasket, and graphene sheets in the heat-conducting gasket are arranged along the thickness direction and have good heat conductivity.
The adhesive has two types, the first adhesive is an adhesive used in an impregnation process, namely the impregnation adhesive, has low viscosity, good fluidity and low hardness after solidification, has good adhesive property on graphene materials, and has good mechanical property; the second adhesive is an adhesive coated on the periphery of the block foam film, is called adhesive glue for short, has high viscosity, general fluidity, high hardness and high strength after solidification, has good adhesive property on the graphene material, and can play a role in fixing a structure.
According to the graphene composite heat-conducting gasket, the thickness of the gasket can be controlled according to a cutting process, and the application requirements of various thicknesses can be met; the graphene sheets in the graphene heat-conducting foam film are vertically arranged along the thickness direction, so that the heat-conducting gasket overall has a higher heat conductivity coefficient in the thickness direction; after the hot pressing process, adhesives are distributed in each layer of foam film and between layers, so that the heat conducting gasket has excellent mechanical property, good rebound resilience, high strength and difficult layering; after the surface polishing process, the roughness of the surface of the gasket is reduced, the surface state is improved, and the bonding degree between the surface of the gasket and the base material is good, so that lower thermal resistance is obtained, and the overall heat conducting performance is improved.
Drawings
FIG. 1 is a schematic diagram of a flow chart of a method for preparing a graphene composite thermal conductive gasket according to the present invention;
FIG. 2 is an SEM image of a graphene thermal conductive foam film according to the present invention;
FIG. 3 is a photograph of a graphene composite thermal conductive gasket according to the present invention;
FIG. 4 is an SEM image of a graphene composite thermal pad according to the present invention;
Fig. 5 is a cross-sectional view of a graphene composite thermal conductive gasket according to the present invention.
Detailed Description
Hereinafter, only certain exemplary embodiments are briefly described. As will be recognized by those of skill in the pertinent art, the described embodiments may be modified in various different ways without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.
In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, the meaning of "a plurality" is two or more, unless specifically defined otherwise.
The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. In order to simplify the present disclosure, components and arrangements of specific examples are described below. They are, of course, merely examples and are not intended to limit the invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, which are for the purpose of brevity and clarity, and which do not themselves indicate the relationship between the various embodiments and/or arrangements discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the application of other processes and/or the use of other materials.
Fig. 1 is a schematic diagram of a flowchart of a preparation method of a graphene composite thermal conductive gasket according to the present invention, and as shown in fig. 1, the preparation method of the graphene composite thermal conductive gasket includes:
Step S1, carrying out laser drilling on a graphene heat-conducting foam film (shown in FIG. 2);
S2, impregnating the perforated graphene heat-conducting foam film with a first adhesive, wherein the graphene heat-conducting foam film is not rolled, has a rough surface and low density, and has larger pores inside, so that the first adhesive is impregnated;
Step S3, stacking the impregnated graphene heat-conducting foam films layer by layer, placing the graphene heat-conducting foam films into a die, and applying pressure to attach adjacent graphene heat-conducting foam films;
Step S4, uniformly coating a second adhesive on the periphery of the pressed graphene heat-conducting foam film, so that the multi-layer graphene heat-conducting foam film is completely coated into a block, wherein the curing temperature of the second adhesive is lower than that of the first adhesive;
step S5, cutting the solidified block into sheets along the stacking direction;
S6, performing hot press molding on the sheet;
Step S7, carrying out surface polishing treatment on the sheet after hot press molding;
And S8, performing edge trimming on the polished sheet, and removing the second adhesive coated on the edge to obtain the graphene composite heat-conducting gasket.
In one embodiment, in step S1, a plurality of through holes are formed in the graphene heat-conducting foam film, wherein the diameter of the through holes is 30-300 μm, preferably 50-200 μm; the average center-to-center spacing of the plurality of through holes is 100 to 600 μm, preferably 200 to 500 μm. The graphene heat-conducting foam film is perforated up and down through laser drilling, so that a large number of through holes can be formed, the first adhesive can permeate into the interlayer inside the foam film from the holes more easily, the binding force inside the foam film is improved, the mechanical property of the gasket is improved, the number of the through holes is determined by the aperture and the hole spacing, the aperture is the diameter of the through holes, the hole spacing is the spacing between the edges of two similar through holes, and a plurality of through holes belong to array distribution.
Preferably, the thermal conductivity of the graphene thermal conductive foam film is not less than 100W/(m·k), and more preferably not less than 150W/(m·k).
Preferably, the thickness of the graphene heat-conducting foam film is 100-300 mu m, and further preferably, the thickness of the graphene heat-conducting foam film is 150-250 mu m.
Preferably, the density of the graphene heat-conducting foam film is 0.05-0.20g/cm 3, and further preferably, the thickness of the graphene heat-conducting foam film is 0.08-0.15g/cm 3.
As shown in fig. 2, the graphene heat-conducting foam membrane is a low-density graphene heat-conducting foam membrane, the internal monolithic layer is well oriented, the pores between the sheets are large, preferably, the average pore diameter of the internal pores of the graphene heat-conducting foam membrane is 10-50 μm, and further preferably, the average pore diameter is 15-30 μm.
In one embodiment, in step S2, the first adhesive is one or more of epoxy resin, phenolic resin, furfural resin, polyurethane, acrylic resin, or silicone gum; preferably, the first adhesive is a silicone gel, further preferably a liquid silicone gel; preferably, the liquid silicone is one or more of polydimethylsiloxane, alpha, omega-dihydroxypolydimethylsiloxane, polydiphenylsiloxane, alpha, omega-dihydroxypolymethyl3, 3-trifluoropropyl siloxane, cyanosiloxysilane, or alpha, omega-diethylpolydimethylsiloxane; preferably, the viscosity of the first adhesive is 50 to 800mpa·s, more preferably 100 to 600mpa·s.
Preferably, the first adhesive is an organic silica gel in a heating curing mode.
In one embodiment, in step S3, the graphene heat-conducting foam film is cut into sheets of uniform size, and the sheets are stacked layer by layer and placed in a mold.
In one embodiment, in step S4, the second adhesive is one or more of epoxy resin, phenolic resin, furfural resin, polyurethane, acrylic resin or silicone gel, preferably epoxy resin, further preferably, the epoxy resin is cured by heating, still further preferably, the epoxy resin is cured by heating at 50 ℃; preferably, the viscosity of the second adhesive is 10000-200000 mPa-s, more preferably 30000-150000 mPa-s.
In one embodiment, in step S5, the cutting mode is not particularly limited, and wire cutting, laser cutting, ultrasonic cutting, blade cutting, freezing cutting, etc. may be used; the thickness of the slice is not particularly required, and the slice is cut according to specific requirements, and is generally the thickness of conventional use, such as 0.2-1mm.
In one embodiment, step S6 includes: limiting the sheet by using a die, heating and curing, hot-press forming, controlling the thickness of the gasket by using the die, heating, pressurizing and curing to obtain the hot-press process effect, for example, a gasket with the thickness of 0.3mm is needed, then a cut sheet with the thickness of 0.4mm (the thickness after prepressing is 75 percent before prepressing) is selected, the cut sheet is placed on the die, the limiting size is adjusted to be 0.3mm, and the hot-press forming process is carried out by selecting proper pressure and temperature, so that the thickness of the gasket after hot pressing is 0.3mm due to the influence of limiting.
Preferably, the applied pressure is selected to be 0.1-1.0MPa, preferably 0.3-0.8MPa, and the pressure is lower than 0.1MPa, so that the effect of leveling the surface of the gasket cannot be achieved due to the fact that the pressure is too small; the pressure is higher than 1.0MPa, so that the graphene sheets in the vertical direction inside the gasket are easily severely extruded and deformed due to the excessive pressure, the heat conduction performance is affected, and the gasket is extruded and cracked due to the excessive pressure; the curing temperature is selected to be 100-160 ℃, preferably 120-150 ℃, if the curing temperature is lower than 100 ℃, the curing of the impregnating glue is easy to be slow, the overall curing effect is affected, if the curing temperature is higher than 160 ℃, the curing reaction is too strong, the product is easy to crack, and if the curing temperature is higher than 200 ℃, the product is easy to age and damage, and the molding is poor.
In one embodiment, in step S7, the polishing process and the polishing apparatus are not particularly limited, and contact polishing, non-contact polishing apparatus and the like may be used, so that the surface roughness is reduced and the adhesion degree between the pad and the substrate is improved without damaging the integrity of the pad, which is beneficial to reducing the interface thermal resistance. The polishing treatment reduces the surface roughness of the material, since the surface roughness has a greater influence on the thermal resistance, the higher the surface roughness, the worse the heat dissipation effect, for the same pad, preferably the roughness Rz < 5um of the pad.
The invention adopts the low-density graphene heat conduction foam film and the adhesive to prepare the heat conduction gasket in a compounding way; the gasket is prepared by adopting the low-density foam film, and is matched with a laser drilling process, so that impregnating adhesive is more beneficial to penetrating into the foam film, and the overall mechanical properties including compression retraction elastic energy and mechanical strength are improved; the second adhesive is coated around the foam film blocks after stacking, pressurizing and bonding, so that the shaping and fixing effects are achieved, and the phenomenon of frame scattering during the cutting process is prevented; because the first adhesive adopts a low-temperature curing process at 50 ℃, and the curing temperature required by the first adhesive is higher, when the first adhesive is cured, the first adhesive is in an uncured state and is in a semi-flowing state only by means of the low-temperature curing process at the earlier stage; after slicing, a hot pressing process is used to make the first adhesive in a semi-flowing state carry out secondary permeation on the inside of the graphene heat conduction foam film, so that a large amount of adhesive exists inside and outside the graphene heat conduction foam film, air holes (air) in the graphene heat conduction foam film are reduced, the first adhesive forms a continuous phase as far as possible, the graphene heat conduction foam film is entirely coated, and the integral mechanical property is improved; the graphene sheets in the graphene heat-conducting foam film are vertically arranged along the thickness direction, so that the heat-conducting gasket overall has a higher heat conductivity coefficient in the thickness direction; during the hot pressing process, part of the second adhesive is extruded and distributed on the surface of the gasket, and a layer of extremely thin adhesive layer is formed after solidification, so that the interface thermal resistance of the gasket is increased, and the overall heat dissipation performance is influenced.
Fig. 3 is a photograph of the graphene composite thermal conductive gasket of the present invention, fig. 4 is an SEM image of the graphene composite thermal conductive gasket of the present invention, and fig. 5 is a cross-sectional view of the graphene composite thermal conductive gasket of the present invention, as shown in fig. 3 to 5, the graphene composite thermal conductive gasket includes a plurality of graphene thermal conductive foam films and an adhesive arranged along a thickness direction sheet, the plurality of through holes are formed on the plurality of graphene thermal conductive foam films, and the graphene thermal conductive foam films occupy 10wt.% to 50wt.%.
Preferably, the graphene thermally conductive foam film comprises 15wt.% to 35wt.%.
As shown in FIG. 4, the graphene composite heat-conducting pad provided by the invention has a smooth surface after polishing and grinding, is beneficial to being attached to a heat dissipation device, and reduces interface thermal resistance.
As shown in FIG. 5, the graphene sheet layer of the graphene composite heat-conducting gasket has a cutting gradient along the thickness direction, so that the compression elastic energy is improved, and the graphene composite heat-conducting gasket has a high heat-conducting property along the thickness direction.
The thermal resistance and compression of the graphene composite heat-conducting gasket (0.2 mm thickness) at 10-100psi are shown in the following table 1:
TABLE 1
Pressure (Psi) 10 20 40 60 80 100
Thermal resistance (K cm 2/W) 0.108 0.086 0.067 0.059 0.056 0.053
Compression amount (%) 10.4 20.1 36.7 49.2 60.7 70.2
Under the conventional use environment (40 psi), the thermal resistance of the graphene composite heat-conducting gasket is lower, the compression amount is only 0.067K & cm 2/W, the compression amount is relatively good and reaches 36.7%, the compression amount is the amount of the gasket which can be compressed under certain pressure, and generally, the better the compression performance of the gasket is, the better the adhesion between the gasket and a base material is, and the lower the thermal resistance is. The compression amount of the graphene composite heat-conducting gasket can reach 70%, so that the bonding degree between the gasket and a device is facilitated, and the heat dissipation performance of the device is improved.
In order to show the comparison effect, in the following specific examples, the thermal conductivity coefficient and the application thermal resistance of the thermal conductive gasket under the condition of 40psi are tested by ASTM D5470, the compression rebound performance of the thermal conductive gasket under the condition of 50% strain is tested by ASTM D575, the compression rebound refers to that the gasket can cause a large compression amount to deform after being stressed, when the force is removed, the gasket can rebound to the compression rebound performance, and the device has the performance of thermal expansion, cold contraction and shaking in the use process, so that the gap between the gasket and the device can be changed, and in order to adapt to the phenomenon, the gasket is required to have good compression retraction elasticity.
Example 1:
in the embodiment, the graphene heat-conducting foam film accounts for 12wt.% and the adhesive accounts for 88wt.%;
the heat conductivity coefficient of the graphene heat-conducting foam film is 205W/(m.K);
The thickness of the graphene heat-conducting foam film is 300 mu m, and the density is 0.19g/cm 3;
the average pore diameter of the internal pores of the graphene heat-conducting foam membrane is 50 mu m;
the graphene heat-conducting foam film has a punching aperture of 300um and a hole spacing of 500um;
The first adhesive is a heat-curable organic silica gel, and the viscosity is 800 mPas;
the second adhesive is a heat-curable epoxy resin, the viscosity is 200000 mPas, and the curing temperature is 50 ℃;
hot pressing process with pressure of 1.0MPa and solidification temperature of 100 ℃;
polishing and grinding the gasket by adopting contact type polishing equipment, and selecting a 500-mesh polishing disc;
Through testing, the thermal conductivity coefficient of the obtained graphene composite thermal conductive gasket is 45W/(m.K), the roughness Rz is 4.559um, and the application thermal resistance and compression rebound resilience of the graphene composite thermal conductive gaskets with different thicknesses are as follows:
Example 2:
in the embodiment, the graphene heat-conducting foam film accounts for 20wt.% and the adhesive accounts for 80wt.%; the heat conductivity coefficient of the graphene heat-conducting foam film is 225W/(m.K);
The thickness of the graphene heat-conducting foam film is 150 mu m, and the density is 0.11g/cm 3;
the average pore diameter of the internal pores of the graphene heat-conducting foam membrane is 30 mu m;
the hole diameter of the graphene heat conduction foam film is 100um, and the hole spacing is 300um;
The first adhesive is a heat-curable organic silica gel, and the viscosity is 500 mPas;
The second adhesive is heat-curable epoxy resin, the viscosity is 100000 mPa.s, and the curing temperature is 50 ℃;
Hot pressing process with pressure of 0.5MPa and solidification temperature of 150 ℃;
polishing and grinding the gasket by adopting contact type polishing equipment, and selecting a 500-mesh polishing disc;
Through testing, the thermal conductivity coefficient of the obtained graphene composite thermal conductive gasket is 73W/(m.K), the roughness Rz is 4.109um, and the application thermal resistance and compression rebound resilience of the graphene composite thermal conductive gaskets with different thicknesses are as follows:
example 3:
In the embodiment, the graphene heat-conducting foam film accounts for 35wt.% and the adhesive accounts for 65wt.%;
the heat conductivity coefficient of the graphene heat-conducting foam film is 145W/(m.K);
The thickness of the graphene heat-conducting foam film is 200 mu m, and the density is 0.08g/cm 3;
the average pore diameter of the internal pores of the graphene heat-conducting foam membrane is 20 mu m;
the hole diameter of the graphene heat conduction foam film is 200um, and the hole spacing is 350um;
The first adhesive is a heat-curable organic silica gel, and the viscosity is 200 mPas;
the second adhesive is heat-curable epoxy resin, the viscosity is 50000 mPa.s, and the curing temperature is 50 ℃;
Hot pressing process with pressure of 0.3MPa and solidification temperature of 120 ℃;
polishing and grinding the gasket by adopting contact type polishing equipment, and selecting a 500-mesh polishing disc;
Through testing, the thermal conductivity coefficient of the obtained graphene composite thermal conductive gasket is 52W/(m.K), the roughness Rz is 3.585um, and the application thermal resistance and compression rebound resilience of the graphene composite thermal conductive gaskets with different thicknesses are as follows:
Example 4:
in this embodiment, the graphene heat-conducting foam film accounts for 50wt.%, and the adhesive accounts for 50wt.%;
the thermal conductivity coefficient of the graphene thermal conductive foam film is 155W/(m.K);
The thickness of the graphene heat-conducting foam film is 180 mu m, and the density is 0.13g/cm 3;
The average pore diameter of the internal pores of the graphene heat-conducting foam membrane is 25 mu m;
the hole diameter of the graphene heat conduction foam film is 80um, and the hole spacing is 200um;
The first adhesive is a heat-curable organic silica gel, and the viscosity is 350 mPa.s;
The second adhesive is heat-curable epoxy resin, the viscosity is 30000 mPas, and the curing temperature is 50 ℃;
hot pressing process with the pressure of 0.6MPa and the curing temperature of 140 ℃;
polishing and grinding the gasket by adopting contact type polishing equipment, and selecting a 500-mesh polishing disc;
Through testing, the thermal conductivity coefficient of the obtained graphene composite thermal conductive gasket is 85W/(m.K), the roughness Rz is 3.211um, and the application thermal resistance and compression rebound resilience of the graphene composite thermal conductive gaskets with different thicknesses are as follows:
example 5:
in this embodiment, the graphene heat-conducting foam film accounts for 25wt.%, and the adhesive accounts for 75wt.%;
the thermal conductivity coefficient of the graphene thermal conductive foam film is 165W/(m.K);
The thickness of the graphene heat-conducting foam film is 250 mu m, and the density is 0.15g/cm 3;
the average pore diameter of the internal pores of the graphene heat-conducting foam membrane is 40 mu m;
The hole diameter of the graphene heat conduction foam film is 150um, and the hole spacing is 400um;
the first adhesive glue is a heat-curing organic silica gel with the viscosity of 600 mPas;
the second adhesive is heat-curable epoxy resin, the viscosity is 150000 mPa.s, and the curing temperature is 50 ℃;
hot pressing process with pressure of 0.8MPa and solidification temperature of 125 ℃;
what polishing is used, the surface roughness after polishing, and other parameters are not given?
Polishing and grinding the gasket by adopting contact type polishing equipment, and selecting a 500-mesh polishing disc;
Through testing, the thermal conductivity coefficient of the obtained graphene composite thermal conductive gasket is 50W/(m.K), the roughness Rz is 3.850 mu m, and the application thermal resistance and compression rebound resilience of the graphene composite thermal conductive gaskets with different thicknesses are as follows:
Comparative example 1:
In this comparative example, the graphene heat-conducting foam film accounts for 40wt.%, the adhesive accounts for 60wt.%;
the thermal conductivity coefficient of the graphene thermal conductive foam film is 165W/(m.K);
The thickness of the graphene heat-conducting foam film is 250 mu m, and the density is 0.15g/cm 3;
the average pore diameter of the internal pores of the graphene heat-conducting foam membrane is 40 mu m;
The hole diameter of the graphene heat conduction foam film is 150um, and the hole spacing is 400um;
the impregnating adhesive is a heat-curing organic silica gel, and the viscosity is 600 mPa.s;
the adhesive is a heat-curable epoxy resin, the viscosity is 150000 mPa.s, and the curing temperature is 50 ℃;
hot pressing process with pressure of 0.8MPa and solidification temperature of 250 ℃;
the gasket is cracked and layered due to the excessively high temperature during the hot pressing process in the comparative example, and cannot be molded.
Comparative example 2:
in this comparative example, the graphene heat-conducting foam film was 50wt.%, the adhesive was 50wt.%;
the thermal conductivity coefficient of the graphene thermal conductive foam film is 155W/(m.K);
The thickness of the graphene heat-conducting foam film is 180 mu m, and the density is 0.13g/cm 3;
The average pore diameter of the internal pores of the graphene heat-conducting foam membrane is 25 mu m;
the hole diameter of the graphene heat conduction foam film is 80um, and the hole spacing is 200um;
the impregnating adhesive is a heating curing type organic silica gel, and the viscosity is 3000 mPa.s;
the adhesive is heat-curable epoxy resin, the viscosity is 30000 mPa.s, and the curing temperature is 50 ℃;
hot pressing process with the pressure of 0.6MPa and the curing temperature of 140 ℃;
through testing, the heat conductivity coefficient of the sample is 70W/(m.K), and the application thermal resistance and compression resilience of samples with different thicknesses are as follows:
Because the impregnating adhesive is too high in the comparative example, the impregnating effect inside the foam film is poor, a large number of air holes exist inside the foam film, and finally the heat conducting performance of the gasket is reduced, and the application thermal resistance is increased; because the foam film is poor in impregnating effect, the impact on the compression rebound resilience performance of the gasket is large, and the compression rebound resilience is seriously reduced.
Comparative example 3:
in the comparative example, the graphene heat-conducting foam film accounts for 20wt.% and the adhesive accounts for 80wt.%;
The thermal conductivity coefficient of the graphene thermal conductive foam film is 255W/(m.K);
The thickness of the graphene heat-conducting foam film is 150 mu m, and the density is 0.41g/cm 3;
the average pore diameter of the internal pores of the graphene heat-conducting foam membrane is 5 mu m;
the hole diameter of the graphene heat conduction foam film is 100um, and the hole spacing is 300um;
the impregnating adhesive is a heat-curing organic silica gel, and the viscosity is 500 mPa.s;
The adhesive is heat-curable epoxy resin, the viscosity is 100000 mPa.s, and the curing temperature is 50 ℃;
Hot pressing process with pressure of 0.5MPa and solidification temperature of 150 ℃;
through testing, the heat conductivity coefficient of the sample is 85W/(m.K), and the application thermal resistance and compression resilience performance of samples with different thicknesses are as follows:
Because the graphene heat-conducting foam film adopted in the comparative example has higher density, the internal pores are smaller, the impregnating effect of the impregnating adhesive is poorer, and a large number of air holes exist in the impregnating adhesive; however, the overall heat conducting property and the applied thermal resistance are not greatly changed due to densification of the foam film; however, the impact on the compression resilience performance of the gasket is large, and the compression resilience is seriously reduced.
Comparative example 4:
in the comparative example, the graphene heat-conducting foam film accounts for 95wt.% and the adhesive accounts for 5wt.%;
the heat conductivity coefficient of the graphene heat-conducting foam film is 400W/(m.K);
The thickness of the graphene heat-conducting foam film is 1000 mu m, and the density is 0.88g/cm 3;
the average pore diameter of the internal pores of the graphene heat-conducting foam membrane is 100 mu m;
the hole diameter of the graphene heat conduction foam film is 100um, and the hole spacing is 300um;
The impregnating adhesive is a heat-curing organic silica gel, and the viscosity is 100 mPa.s;
The adhesive is heat-curable epoxy resin, the viscosity is 300000 mPa.s, and the curing temperature is 80 ℃;
hot pressing process with pressure of 2.0MPa and solidification temperature of 150 ℃;
Through testing, the heat conductivity coefficient of the sample is 295W/(m.K), and the application thermal resistance and compression resilience performance of samples with different thicknesses are as follows:
Although the thermal resistance of the gasket is lower by only 0.07K cm 2/W under the 40psi pressure test, the compression amount is poor, only 10%, and the compression rebound resilience performance is poor, namely 40.2%, so that the gasket has poor bonding degree between the gasket and the device due to the unevenness of the surface of the device in the actual use process, the actual use effect is poor, and the expected heat dissipation effect cannot be achieved.
Because the graphene heat conduction foam film adopted in the comparative example occupies a relatively large area, the internal adhesive is less, so the internal bonding force is weak, the overall strength of the gasket is relatively poor, and the long service life of the gasket is influenced.
Comparative example 5:
in the embodiment, the graphene heat-conducting foam film accounts for 12wt.% and the adhesive accounts for 88wt.%;
the heat conductivity coefficient of the graphene heat-conducting foam film is 205W/(m.K);
The thickness of the graphene heat-conducting foam film is 300 mu m, and the density is 0.19g/cm 3;
the average pore diameter of the internal pores of the graphene heat-conducting foam membrane is 50 mu m;
The graphene heat-conducting foam film is not perforated;
The first adhesive is a heat-curable organic silica gel, and the viscosity is 800 mPas;
the second adhesive is a heat-curable epoxy resin, the viscosity is 200000 mPas, and the curing temperature is 50 ℃;
hot pressing process with pressure of 1.0MPa and solidification temperature of 100 ℃;
because this comparative example does not adopt the laser drilling, the inside of gasket does not have the impregnating adhesive to get into to overall mechanical properties is relatively poor, when the gasket polishes the grinding, appears the phenomenon that the gasket ftractures and falls apart, namely indicates that the mechanical properties of gasket can't maintain the going on of polishing grinding technology this moment, and the experiment fails.
Comparative example 6:
In the embodiment, the graphene heat-conducting foam film accounts for 35wt.% and the adhesive accounts for 65wt.%;
the heat conductivity coefficient of the graphene heat-conducting foam film is 145W/(m.K);
The thickness of the graphene heat-conducting foam film is 200 mu m, and the density is 0.08g/cm 3;
the average pore diameter of the internal pores of the graphene heat-conducting foam membrane is 20 mu m;
the hole diameter of the graphene heat conduction foam film is 200um, and the hole spacing is 350um;
The first adhesive is a heat-curable organic silica gel, and the viscosity is 200 mPas;
the second adhesive is heat-curable epoxy resin, the viscosity is 50000 mPa.s, and the curing temperature is 50 ℃;
Hot pressing process with pressure of 0.3MPa and solidification temperature of 120 ℃;
polishing and grinding the gasket;
through testing, the thermal conductivity coefficient of the obtained graphene composite thermal conductive gasket is 52W/(m.K), the roughness Rz is 22.125um, and the application thermal resistance and compression rebound resilience of the graphene composite thermal conductive gaskets with different thicknesses are as follows:
The test shows that the surface state of the unpolished and polished pad is poor, the roughness value is high (Rz is more than 20 um), and the interface thermal resistance of the pad is large, so that the application thermal resistance is large, and the heat dissipation effect is poor.
The heat conductivity coefficient is taken as a reference, the current heat conductivity coefficient is more than or equal to 30W/(m.K), namely the high heat conductivity gasket is just one reference meaning, the current gasket with the thickness of 0.2mm has specific requirements on the application of heat resistance and compression rebound, the heat resistance (the pressure is 40 psi) is less than or equal to 0.12 (K.cm 2/W), and the compression rebound performance is more than or equal to 80%. The gasket is mainly applied to the fields of 5G communication, high-power chips and electric automobiles. If the thermal resistance is too high (more than 0.12), the heat dissipation effect is poor, the heat dissipation of the whole heat dissipation system is influenced, and the heat dissipation effect of a chip is mainly influenced, so that the service life of the chip is reduced, and the use effect is influenced; because the cooling system is in the state of cold and heat exchange for a long time, the gap filled by the gasket can also change due to the cold and heat exchange, the gap can be enlarged or reduced, so that the gasket is required to change along with the change of the gap, the gasket has good compression retraction elasticity and can adapt to the change of the environment, when the compression rebound resilience of the gasket is less than 80%, the gasket cannot adapt to the change of the environmental gap, the bonding degree of the gasket and the upper base material and the lower base material is reduced, and thus heat cannot be conducted out through the gasket, the overall cooling effect is influenced, and the service life of the cooling system is even influenced.
The preparation method of the graphene composite heat-conducting gasket adopts a process of immersing and slicing and then hot-pressing, so that the content of graphene in the gasket is ensured, the dosage of the adhesive is increased, the hollow (air) in the foam film is reduced, the adhesive forms a continuous phase as far as possible, the foam film is integrally coated, and the integral mechanical properties including the mechanical strength and compression retraction elasticity of the gasket are improved.
The polishing process of the graphene composite heat-conducting gasket surface is beneficial to reducing the surface roughness, is beneficial to improving the bonding degree of the gasket surface and a base material in the actual use process, reduces the interface thermal resistance and improves the overall heat-conducting performance.
The above embodiments according to the present invention are illustrative, and various changes and modifications may be made by the person skilled in the art without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the contents of the specification, and must be determined according to the scope of the claims.

Claims (31)

1. The preparation method of the graphene composite heat-conducting gasket is characterized by comprising the following steps of:
carrying out laser drilling on the graphene heat conduction foam film;
Impregnating the perforated graphene heat-conducting foam film through a first adhesive;
Stacking the impregnated graphene heat-conducting foam films layer by layer, placing the graphene heat-conducting foam films into a die, and applying pressure to attach adjacent graphene heat-conducting foam films;
Uniformly coating a second adhesive on the periphery of the pressed graphene heat-conducting foam film to enable the multi-layer graphene heat-conducting foam film to be completely coated into a block, wherein the curing temperature of the second adhesive is lower than that of the first adhesive;
Cutting the cured and formed block into sheets along the stacking direction;
Carrying out hot press molding on the sheet;
Carrying out surface polishing treatment on the sheet after hot press molding;
Trimming the edge of the polished sheet, and removing the second adhesive coated on the edge to obtain a graphene composite heat-conducting gasket;
the graphene heat-conducting foam film accounts for 10wt.% to 35wt.%;
In the step of carrying out laser drilling on the graphene heat-conducting foam film, a plurality of through holes are formed in the graphene heat-conducting foam film, and the diameter of each through hole is 30-300 mu m; the viscosity of the first adhesive is 50-800 mPa.s; the viscosity of the second adhesive is 10000-200000 mPa.s; the thickness of the graphene heat-conducting foam film is 100-300 mu m; the average pore diameter of the pores in the graphene heat-conducting foam membrane is 10-50 mu m.
2. The method of claim 1, wherein the diameter of the through hole is 50-200 μm.
3. The method of manufacturing according to claim 2, wherein the plurality of through holes have an average center-to-center spacing of 100-600 μm.
4. The method of claim 3, wherein the plurality of through holes have an average center-to-center spacing of 200-500 μm.
5. The method according to claim 1, wherein in the step of impregnating the perforated graphene heat-conducting foam film with a first adhesive, the first adhesive is one or more of epoxy resin, phenolic resin, furfural resin, polyurethane, acrylic resin, and silicone gel.
6. The method of claim 5, wherein the first adhesive is a silicone gel.
7. The method of claim 6, wherein the first adhesive is a liquid silicone gel.
8. The method of claim 7, wherein the first adhesive is a liquid silicone gel cured by heating.
9. The method of claim 7, wherein the liquid silicone is one or more of polydimethylsiloxane, alpha, omega-dihydroxypolydimethylsiloxane, polydiphenylsiloxane, alpha, omega-dihydroxypolymethyl3, 3, 3-trifluoropropyl siloxane, cyanosiloxysilane, or alpha, omega-diethylpolydimethylsiloxane.
10. The method of claim 1, wherein the first adhesive has a viscosity of 100-600 mPa-s.
11. The method according to claim 1, wherein in the step of stacking the impregnated graphene heat-conducting foam films layer by layer and placing them in a mold, pressing to bond the films together, the graphene heat-conducting foam films are cut into sheets with uniform sizes, and the sheets are stacked layer by layer and placed in the mold.
12. The preparation method of claim 1, wherein in the step of uniformly coating the second adhesive on the periphery of the graphene heat-conducting foam film after the pressing, the second adhesive is one or more of epoxy resin, phenolic resin, furfural resin, polyurethane, acrylic resin or organic silica gel.
13. The method of claim 12, wherein the second adhesive is epoxy resin.
14. The method of claim 13, wherein the epoxy resin is cured by heating.
15. The method of claim 14, wherein the epoxy resin is cured by heating at 50 ℃.
16. The method according to claim 1, wherein the second adhesive is 30000 to 150000 mPa-s.
17. The method according to claim 1, wherein in the step of cutting the solidified and molded block into sheets in the lamination direction, wire cutting, laser cutting, ultrasonic cutting, blade cutting, or freeze cutting is used.
18. The method of claim 17, wherein the block is cut into sheets having a thickness of 0.2-1mm.
19. The method of claim 1, wherein the step of hot press forming the sheet comprises: and limiting the sheet by using a die and heating and curing the sheet.
20. The method of claim 19, wherein the hot press forming has an applied pressure of 0.1 to 1.0MPa.
21. The method of claim 20, wherein the applied pressure is 0.3-0.8MPa.
22. The method of claim 19, wherein the curing temperature is 100-160 ℃.
23. The method of claim 22, wherein the curing temperature is 120-150 ℃.
24. The method according to claim 1, wherein the step of subjecting the sheet after hot press molding to a surface polishing treatment comprises: the polishing mode adopts contact polishing or non-contact polishing equipment.
25. The method according to claim 1, wherein in the step of laser drilling the graphene heat-conducting foam film, a heat conductivity coefficient of the graphene heat-conducting foam film is not less than 100W/(m-K).
26. The method of claim 25, wherein the graphene thermal conductive foam film has a thermal conductivity of not less than 150W/(m-K).
27. The method of claim 1, wherein the graphene thermally conductive foam film has a thickness of 150-250 μm.
28. The method of claim 1, wherein the graphene thermally conductive foam film has a density of 0.05-0.20g/cm 3.
29. The method of claim 28, wherein the graphene thermally conductive foam film has a density of 0.08-0.15g/cm 3.
30. The preparation method according to claim 1, wherein the graphene heat-conducting foam membrane has an average pore size of 15-30 μm.
31. The graphene composite heat-conducting gasket is characterized by being prepared by a preparation method according to any one of claims 1-30, and comprises a plurality of layers of graphene heat-conducting foam films and an adhesive, wherein the layers of graphene heat-conducting foam films are arranged along the thickness direction, and the plurality of through holes are formed in the layers of graphene heat-conducting foam films.
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